Aqueous dispersions for antioxidants

ABSTRACT

The present invention relates to aqueous dispersions for solid phenolic antioxidants, wherein the antioxidants are dispersed in the aqueous phase with polyvinyl alcohol as dispersing agent. The invention also relates to a process, which comprises stabilising a polymer material against oxidative, thermal or light-induced degradation by adding to the polymer the aqueous dispersion.

The present invention relates to aqueous dispersions for solid phenolic antioxidants, a process for preparing the aqueous dispersions, the further processing of the aqueous dispersion and a polymer composition comprising the dispersed components of the aqueous dispersion. The invention particularly relates to storage-stable, non-sedimenting emulsions comprising phenolic antioxidants, for example for use for stabilising emulsion-polymerised polymers and copolymers against atmospheric oxidative reactions.

Solid additives, such as certain commercial phenolic antioxidants from the Irganox® (trade mark of Ciba Specialty Chemicals) series, e.g. IRGANOX 1076: Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate, are used for a great variety of technical applications, e.g. for the stabilisation of polymers against oxidative, thermal or light induced degradation. A small particle size is preferred to assure the efficiency of the additive used. The ideal particle size should be mainly in the range from 0.1 to 10.0μ. Any particle size smaller than 5.0μ is particularly preferred.

Wet grinding, as opposed to grinding of dry particles, is a standard method for obtaining particles of this small size. This method combines the advantages of a reduction to small particles with the preparation of a dispersion comprising the particles in an inert liquid. Such dispersions are preferably prepared from solids by grinding within deionised water as the dispersant phase and require the presence and/or subsequent addition of various additives, such as surfactants, thickeners, and fungicides, to ensure the mechanical and chemical stabilisation of the dispersion. The solids are prepared by work-up methods, such as crystallisation, filtration, drying or grinding, in a sequential step subsequent to their synthesis. The present invention intends to replace the wet grinding step with a more convenient and feasible step for reducing the particle size.

It has surprisingly been found that converting phenolic antioxidants to an aqueous dispersion, particularly to an emulsion, reduces the particle size of solid phenolic antioxidants even further to the size of small droplets. It has not been known before that a melt prepared from solid material of phenolic antioxidants of the formula (I) is dispersible as an emulsion in an aqueous phase wherein the non-ionic surfactant polyvinyl alcohol is dispersed. The preparation of a molten phase and its subsequent dispersion to give an emulsion is clearly more beneficial than the standard method of isolating a solid, e.g. by crystallisation, and its subsequent wet grinding.

The present invention relates to an aqueous dispersion comprising

-   -   a) A compound of the formula:

-   -   Wherein     -   One of R₁ and R₂ independently of one another represents         hydrogen or C₁–C₄alkyl and the other one represents C₃–C₄alkyl;     -   x represents zero (direct bond) or a numeral from one to three;         and     -   R₃ represents C₈–C₂₂alkyl; or groups of the partial formulae

-   -   Wherein     -   One of R₁′ and R₂′ independently of one another represents         hydrogen or C₁–C₄alkyl and the other one represents C₃–C₄alkyl;     -   x represents zero (direct bond) or a numeral from one to three;         and     -   y represents a numeral from two to six;     -   b) Polyvinyl alcohol having a degree of polymerisation of about         500–2500 and a degree of hydrolysis of about 70.0–99.9%; and,         optionally, further additives; and     -   c) Water.

The general terms used in the description of the instant invention, unless defined otherwise, are defined as follows:

The term aqueous dispersion comprises any mixture of two phases wherein dispersed particles are distributed homogeneously in a dispersant phase (dispergens), which in the instant case is water.

The term aqueous dispersion is defined within the limits of so-called solid/liquid or liquid/liquid disperse systems, e.g. emulsion, dispersion, as opposed to other types of dispersions, such as solid/gas, e.g. fumes, or gas/liquid, e.g. foams, dispersions. Solid/liquid dispersions that apply here consist of a two-phase system containing insoluble solid particles or solid particles of low solubility within a liquid. Liquid/liquid dispersions are commonly defined as emulsions and consist of two separate phases of different polarity. In the instant case a non-polar phase is dispersed in the polar phase, which is water.

The term dispersed particles comprises solid and, in particular, liquid particles, in the instant case the compound of the formula (I), to be distributed homogeneously within a liquid phase, e.g. water. Homogeneous distribution means that the concentration of the solid or liquid particles within the liquid dispersion agent is identical or approximately identical in any volume fraction of that liquid phase (even distribution of liquid or solid particles).

Component a)

In a compound of the formula (I) R₁ and R₂ defined as C₁–C₄alkyl comprise the unbranched and branched (where possible) groups methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl.

R₁ and R₂ defined as C₃–C₄alkyl comprises the unbranched and preferably branched groups, e.g. isopropyl, isobutyl or tert-butyl.

In a preferred embodiment of the invention one of R₁ and R₂ represents hydrogen or C₁–C₄alkyl, particularly methyl or tert-butyl, and the other one represents C₃–C₄alkyl, particularly tert-butyl.

The numeral x represents zero or a numeral from one to three.

In the event that x is zero, the direct bond is defined.

In the event that x is one, the group C_(x)H_(2x), represents methylene.

In the event that x represents the numeral two, the group —[C_(x)H_(2x)]— represents 1,1- or preferably 1,2-ethylene.

In the event that x represents the numeral three, the group —[C_(x)H_(2x)]— represents 1,1-, 1,2- or preferably 1,3-propylene.

R₃ defined as C₈–C₂₂alkyl represents, for example n-octyl, 2-ethylhexyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, n-nonyl or 1,1,3-trimethylhexyl or C₁₀–C₂₂alkyl, particularly straight chain C₁₀–C₂₂alkyl, e.g. n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl or n-octadecyl or higher homologues thereof.

A particularly preferred compound, wherein R₁ and R₂ represent tert-butyl, R₃ represents C₁₀–C₂₂alkyl, particularly n-octadecyl, and x is the numeral two, is IRGANOX 1076: n-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

In a compound (I) wherein R₃ represents groups of the partial formulae (A) and (B), R₁′ and R₂′ have the same meanings as defined above with regard to R₁ and R₂. Preferably one of R₁′ and R₂′ represents methyl or tert-butyl and the other one represents C₃–C₉alkyl, particularly tert-butyl.

In a compound (I) wherein R₃ represents the group of the partial formula (A), y represents a numeral from two to six, preferably three.

A particularly preferred compound (I), wherein one of R₁ and R₂ represents methyl and the other one represents tert-butyl, x represents two, R₃ represents a group of the partial formula A, wherein R₁′ and R₂′ are as defined as R₁ and R₂, x represents two and y represents three, is IRGANOX 245: ethylene-bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate].

A particularly preferred compound (I), wherein R₁ and R, represents tert-butyl, x represents three and R₃ represents a group of the partial formula B, wherein R₁′ and R₂′ are as defined as R₁ and R₂ and x represents two, is IRGANOX 1010: tetrakis[3-(3,5-di-tert-butyl-4-hydroxy-phenyl)-propionate].

Component b)

Suitable polyvinyl alcohols are obtainable by hydrolysis of polyvinyl acetate and have a mean molar mass of approximately 15 000 to 250 000, which corresponds to a degree of polymerisation of about 500–2500. Suitable polyvinyl alcohols have a degree of hydrolysis of about 70.0–99.9 mol % and are characterised by their viscosity (of a 4% aqueous solution) according to DIN 53 015 from 2.5 to 60.0 [mPa·s]. The ester value according to DIN 53 401 decreases from 220 to 8.0 [mg KOH/g] and the residual acetyl content from 17.0 to 0.2% by weight with an increasing degree of hydrolysis.

Suitable polyvinyl alcohols are the commercial products obtainable under the trademark Mowiol® (Clariant GmbH, D-65926 Frankfurt). Special reference is made to the products 3- and 15–96; 3-, 4-, 6-, 10-, 20- and 56–98; or 15- and 28–99 (fully hydrolysed grades).

Particularly preferred are the commercial products 15–79; 3–83; 4-, 5-, 8-, 18-, 23-, 26-, 40-, 47- and 56–88; 30–92 (partially hydrolysed grades).

Component c)

Water is present in the dispersion as the remainder to make 100.0% by weight. The addition of purified, e.g. deionised or distilled, water is preferred.

The aqueous dispersion of the invention may comprise additional additives suitable for use in polymers, preferably additives customarily used for improving the chemical and physical properties of polymers containing these additives. The auxiliaries can be present in the dispersion in varying proportions, for example, in amounts of up to 40.0% by weight, preferably from 0.05% to 40.0% by weight, more preferably from 0.05% to 25.0% by weight, with particular preference from 0.05% to 10.0% by weight based on the total weight of the composition. Suitable groups of additional additives are listed up here by way of example: antioxidants selected from the group consisting of alkylated monophenols, alkylthiomethylphenols, hydroquinones and alkylated hydroquinones, tocopherols, hydroxylated thiodiphenyl ethers, alkylidene-bis-phenols, O-, N- and S-benzyl compounds, hydroxybenzylated malonates, aromatic hydroxybenzyl compounds, triazine compounds, benzylphosphonates, acylaminophenols, esters and amides of β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid, β-(3,5-di-t-butyl-4-hydroxy-3-methylphenyl)-propionic acid, or β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid, ascorbic acid, aminic antioxidants, light stabilisers, phosphites, phosphines, phosponites, hydroxylamines, nitrones, thiosynergists, peroxide scavengers, polyamide stabilisers, basic co-stabilisers, nucleating agents, fillers and reinforcing agents, plasticisers, lubricants, emulsifiers, pigments, rheological additives, levelling assistants, optical brighteners, flame proofing agents, antistatic agents, blowing agents, benzofuranones and indolinones.

Suitable additives optionally present in the aqueous dispersion according to the present invention may be selected from the following non-exhaustive list of specific additives:

-   1. Antioxidants -   1.1. Alkylated monophenols, for example     2,6-di-t-butyl-4-methylphenol, 2-butyl-4,6-dimethyl-phenol,     2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butyl-4-n-butylphenol,     2,6-di-t-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol,     2-(l-methylcyclohexyl)-4,6-dimethylphenol,     2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol,     2,6-di-t-butyl-4-methoxymethylphenol, linear or side chain-branched     nonylphenols; such as 2,6-dinonyl-4-methylphenol,     2,4-dimethyl-6-(1-methylundec-1′-yl)phenol,     2,4-dimethyl-6-(1′-methylheptadec-1′-yl)-phenol,     2,4-dimethyl-6-(1′-methyltridec-1′-yl)phenol and mixtures thereof. -   1.2. Alkylthiomethylphenols, for example     2,4-dioctylthiomethyl-6-t-butylphenol,     2,4-dioctylthiomethyl-6-methylphenol,     2,4-dioctylthiomethyl-6-ethylphenol,     2,6-didodecylthiomethyl-4-nonylphenol. -   1.3 Hydroquinones and alkylated hydroquinones, for example     2,6-di-t-butyl-4-methoxyphenol, 2,5-di-t-butylhydroquinone,     2,5-di-t-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol,     2,6-di-t-butylhydroquinone, 2,5-di-t-butyl-4-hydroxyanisole,     3,5-di-t-butyl-4-hydroxyanisole, 3,5-di-t-butyl-4-hydroxyphenyl     stearate, bis(3,5-di-t-butyl-4-hydroxyphenyl)adipate. -   1.4. Tocopherols, for example α-, β-, γ- or δ-tocopherols and     mixtures thereof (vitamin E). -   1.5. Hydroxylated thiodiphenyl ethers, for example     2,2′-thio-bis(6-t-butyl-4-methylphenol),     2,2′-thio-bis(4-octylphenol),     4,4′-thio-bis(6-t-butyl-3-methylphenol),     4,4′-thio-bis(6-t-butyl-2-methylphenol),     4,4′-thio-bis(3,6-di-sec-amylphenol),     4,4′-bis(2,6-dimethyl-4-hydroxyphenyl) disulphide. -   1.6. Alkylidene-bis-phenols, for example     2,2′-methylene-bis(6-t-butyl-4-methylphenol),     2,2′-methylene-bis(6-t-butyl-4-ethylphenol),     2,2′-methylene-bis[4-methyl-6-(l-methylcyclohexyl)phenol],     2,2′-methylene-bis(4-methyl-6-cyclohexylphenol),     2,2′-methylene-bis(6-nonyl-4-methylphenol),     2,2′-methylene-bis(4,6-di-t-butylphenol),     2,2′-ethylidene-bis(4,6-di-t-butylphenol),     2,2′-ethylidene-bis(6-t-butyl-4-isobutylphenol),     2,2′-methylene-bis[6-(α-methylbenzyl)-4-nonylphenol],     2,2′-methylene-bis[6-(α,α-dimethylbenzyl)-4-nonylphenol],     4,4′-methylene-bis(2,6-di-t-butylphenol),     4,4′-methylene-bis(6-t-butyl-2-methylphenol),     1,1-bis(5-t-butyl-4-hydroxy-2-methylphenyl)butane,     2,6-bis(3-t-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol,     1,1,3-tris(5-t-butyl-4-hydroxy-2-methylphenyl)butane,     1,1-bis(5-t-butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane,     ethylene glycol bis[3,3-bis(3′-t-butyl-4′-hydroxyphenyl)butyrate],     bis(3-t-butyl-4-hydroxy-5-methylphenyl)dicyclopentadiene,     bis[2-(3′-t-butyl-2′-hydroxy-5′-methylbenzyl)-6-t-butyl-4-methylphenyl]terephthalate,     1,1-bis(3,5-dimethyl-2-hydroxyphenyl)butane,     2,2-bis(3,5-di-t-butyl-4-hydroxyphenyl)propane,     2,2-bis(5-t-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercaptobutane,     1,1,5,5-tetra-(5-t-butyl-4-hydroxy-2-methylphenyl)pentane. -   1.7. O-, N- and S-benzyl compounds, for example,     3,5,3′,5′-tetra-t-butyl-4,4′-dihydroxydibenzyl ether, octadecyl     4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tridecyl     4-hydroxy-3,5-di-t-butylbenzylmercaptoacetate,     tris(3,5-di-t-butyl-4-hydroxybenzyl)-amine,     bis(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate,     bis(3,5-di-t-butyl-4-hydroxybenzyl) sulphide, isooctyl     3,5-di-t-butyl-4-hydroxybenzylmercaptoacetate. -   1.8. Hydroxybenzylated malonates, for example dioctadecyl     2,2-bis(3,5-di-t-butyl-2-hydroxybenzyl)malonate, dioctadecyl     2-(3-t-butyl-4-hydroxy-5-methylbenzyl)malonate, didodecyl     mercaptoethyl-2,2-bis(3,5-di-t-butyl-4-hydroxybenzyl)malonate,     di-[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2bis(3,5-di-t-butyl-4-hydroxybenzyl)malonate. -   1.9. Aromatic hydroxybenzyl compounds, for example     1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,     1,4-bis(3,5-di-t-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene,     2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)phenol. -   1.0. Triazine compounds, for example     2,4-bisoctylmercapto-6-(3,5-di-t-butyl-4-hydroxyanilino)-1,3,5-triazine,     2-octylmercapto-4,6-bis(3,5-di-t-butyl-4-hydroxyanilino)-1,3,5-triazine,     2-octylmercapto-4,6-bis(3,5-di-t-butyl-4-hydroxyphenoxy)-1,3,5-triazine,     2,4,6-tris(3,5-di-t-butyl-4-hydroxyphenoxy)-1,2,3-triazine,     1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate,     1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate,     2,4,6-tris(3,5-di-t-butyl-4-hydrophenylethyl)-1,3,5-triazine,     1,3,5-tris(3,5-di-t-butyl-4-hydroxyphenylpropionyl)hexahydro-1,3,5-triazine,     1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate. -   1.11. Benzylphosphonates, for example dimethyl     2,5-di-t-butyl-4-hydroxybenzyl-phosphonate, diethyl     3,5-di-t-butyl-4-hydroxybenzylphosphonate, dioctadecyl     3,5-di-t-butyl-4-hydroxybenzylphosphonate, dioctadecyl     5-t-butyl-4-hydroxy-3-methylbenzylphosphonate, the calcium salt of     the monoethyl ester of 3,5-di-t-butyl-4-hydroxybenzylphosphonic     acid. -   1.12. Acylaminophenols, for example 4-hydroxylauranilide,     4-hydroxystearanilide, octyl     N-(3,5-di-t-butyl-4-hydroxyphenyl)carbamate. -   1.13. Esters of β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid     with mono- or polyhydric alcohols, e.g. with methanol, ethanol,     n-octanol, 1-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol,     ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene     glycol, diethylene glycol, triethylene glycol, pentaerythritol,     tris(2-hydroxyethyl)isocyanurate, N,N′-bis(2-hydroxyethyl)oxalamide,     3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,     trimethylolpropane,     4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. -   1.14. Esters of β-(5-t-butyl-4-hydroxy-3-methylphenyl)propionic acid     with mono- or polyhydric alcohols, e.g. with methanol, ethanol,     n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol,     ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene     glycol, diethylene glycol, triethylene glycol, pentaerythritol,     tris(2-hydroxyethyl)isocyanurate, N,N′-bis(2-hydroxyethyl)oxalamide,     3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,     trimethylolpropane,     4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. -   1.15. Esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid     with mono- or polyhydric alcohols, e.g. with methanol, ethanol,     octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene     glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol,     diethylene glycol, triethylene glycol, pentaerythritol,     tris(2-hydroxyethyl)isocyanurate, N,N′-bis(2-hydroxyethyl)oxalamide,     3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,     trimethylolpropane,     4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. -   1.16. Esters of 3,5-di-t-butyl-4-hydroxyphenylacetic acid with mono-     or polyhydric alcohols, e.g. with methanol, ethanol, octanol,     octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,     1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene     glycol, triethylene glycol, pentaerythritol,     tris(2-hydroxyethyl)isocyanurate,     N,N′-bis(2-hydroxyethyl)-oxalamide, 3-thiaundecanol,     3-thiapentadecanol, trimethylhexanediol, trimethylolpropane,     4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane. -   1.17. Amides of β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid,     e.g.     N,N′-bis(3,5-di-t-butyl-4-hydroxyphenylpropionyl)hexamethylenediamide,     N,N′-bis(3,5-di-t-butyl-4-hydroxyphenylpropionyl)trimethylenediamide,     N,N′-bis(3,5-di-t-butyl-4-hydroxyphenylpropionyl)hydrazide,     N,N′-bis[2-(3-[3,5-di-t-butyl-4-hydroxyphenyl]propionyloxy)ethyl]oxamide     (Naugard® XL-1 from Uniroyal). -   1.18. Ascorbic acid (vitamin C). -   1.19. Aminic antioxidants, for example     N,N′-diisopropyl-p-phenylenediamine,     N,N′-di-sec-butyl-p-phenylenediamine,     N,N′-bis(1,4-dimethyl-pentyl)-p-phenylenediamine,     N,N′-bis(1-ethyl-3-methyl-pentyl)-p-phenylenediamine,     N,N′-bis(1-methylheptyl)-p-phenylenediamine,     N,N′-dicyclohexyl-p-phenylenediamine,     N,N′-diphenyl-p-phenylenediamine,     N,N′-di-(2-naphthyl)-p-phenylenediamine,     N-isopropyl-N′-phenyl-p-phenylenediamine,     N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine,     N-(1-methylheptyl)-N′-phenyl-p-phenylenediamine,     N-cyclohexyl-N′-phenyl-p-phenylenediamine,     4-(p-toluenesulphonamido)-diphenylamine,     N,N′-dimethyl-N,N′-di-sec-butyl-p-phenylenediamine, diphenylamine,     N-allyldiphenylamine, 4-isopropoxydiphenylamine,     N-phenyl-1-naphthylamine, N-(4-t-octylphenyl)-1-naphthylamine,     N-phenyl-2-naphthylamine, octylated diphenylamine, for example     p,p′-di-t-octyldiphenyl -amine, 4-n-butylaminophenol,     4-butyrylaminophenol, 4-nonanoylaminophenol,     4-dodecanoylaminophenol, 4-octadecanoylaminophenol,     di-(4-methoxyphenyl)amine,     2,6-di-t-butyl-4-dimethylaminomethylphenol,     2,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane,     N,N,N′,N′-tetramethyl-4,4′-diamino-diphenylmethane,     1,2-di[(2-methylphenyl)amino]ethane, 1,2-diphenylaminopropane,     (o-tolyl)biguanide, di-[4-(1′,3′-dimethylbutyl)phenyl]amine,     t-octylated N-phenyl-1-naphthylamine, a mixture of mono- and     dialkylated t-butyl/t-octyldiphenylamines, a mixture of mono- and     dialkylated nonyldiphenylamines, a mixture of mono- and dialkylated     dodecyldiphenylamines, a mixture of mono- and dialkylated     isopropyl/isohexyl-diphenylamines, mixtures of mono- and dialkylated     t-butyldiphenylamines,     2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, a     mixture of mono- and dialkylated t-butyl/t-octyl-phenothiazines, a     mixture of mono- and dialkylated t-octyl-phenothiazines,     N-allylphenothiazine, N,N,N′,N′-tetraphenyl-1,4-diaminobut-2-ene,     N,N-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine,     bis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate,     2,2,6,6-tetramethylpiperidin-4-one and     2,2,6,6-tetramethylpiperidin-4-ol. -   1.20. Polyphenolic antioxidants, for example derivates of p-cresol     and dicyclopentadiene for example ®WINGSTAY L (Goodyear), CAS-Nb     68610-51-5. -   2. UV-absorbers and Light Stabilisers -   2.1.2-(2′-Hydroxyphenyl)benzotriazoles, for example     2-(2′-hydroxy-5′-methylphenyl)benzotriazole,     2-(3′,5′-di-tert-butyl-2′-hydroxyphenyl)benzotriazole,     2-(5′-tert-butyl-2′-hydroxyphenyl)benzotriazole,     2-(2′-hydroxy-5′-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole,     2-(3′,5′-di-tert-butyl-2′-hydroxyphenyl)-5-chlorobenzotriazole,     2-(3′-tert-butyl-2′-hydroxy-5′-methylphenyl)-5-chlorobenzotriazole,     2-(3′-sec-butyl-5′-tert-butyl-2′-hydroxyphenyl)benzotriazole,     2-(2′-hydroxy-4′-octyloxyphenyl)benzotriazole,     2-(3′,5′-di-tert-amyl-2′-hydroxyphenyl)benzotriazole,     2-(3′,5′-bis(α,α-dimethylbenzyl)-2′-hydroxyphenyl)benzotriazole,     2-(3′-tert-butyl-2′-hydroxy-5-(2-octyloxycarbonylethyl)phenyl-5-chlorobenzotriazole,     2-(3′-tert-butyl-5′-[2-(2-ethylhexyloxy)carbonylethyl]-2′-hydroxyphenyl)-5-chlorobenzotriazole,     2-3′-tert-butyl-2′-hydroxy-5′-(2-methoxycarbonylethyl)phenyl)-5-chlorobenzotriazole,     2-(3′-tert-butyl-2′-hydroxy-5′-(2-methoxycarbonylethyl)phenyl)benzotriazole,     2-(3′-tert-butyl-2′-hydroxy-5′-(2-octyloxycarbonylethyl)phenyl)benzotriazole,     -2-(3′-tert-butyl-5′[2-(2-ethylhexyloxy)carbonylethyl]-2′-hydroxyphenyl)benzotriazole,     2-(3′-tert-butyl-5′-[2-(2-ethylhexyloxy)carbonylethyl]-2′-hydroxyphenyl)benzotriazole,     2-(3′-dodecyl-2′-hydroxy-5′-methylphenyl)-benzotriazole,     2-(3′-tert-butyl-2′-hydroxy-5′-(2-isooctyloxycarbonylethyl)phenylbenzotriazole,     2,2′-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-benzotriazole-2-ylphenol];     the transesterification product of     2-[3′-tert-butyl-5′-(2-methoxycarbonylethyl)-2′-hydroxy-phenyl]-2H-benzotriazole     with polyethylene glycol 300; R—CH₂CH₂—COO—CH₂CH₂     ₂, wherein R represents     3′-tert-butyl-4′-hydroxy-5′-2H-benzotriazol-2-ylphenyl,     2-[2′-hydroxy-3′(α,α-dimethylbenzyl)-5′-(1,1,3,3-tetramethylbutyl)phenyl]benzotriazole;     2[2′-hydroxy-3′-(1,1,3,3-tetramethylbutyl)-5′-(α,α-dimethylbenzyl)phenyl]benzotriazole. -   2.2.2-Hydroxybenzophenones, for example the 4-hydroxy, 4-methoxy,     4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy,     4,2′,4′-trihydroxy and 2′-hydroxy-4,4′-dimethoxy derivatives. -   2.3. Esters of substituted and unsubstituted benzoic acids, for     example 4-tert-butylphenyl salicylate, phenyl salicylate,     octylphenyl salicylate, dibenzoyl resorcinol,     bis(4-tert-butylbenzoyl)resorcinol, benzoyl resorcinol,     2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate,     hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl     3,5-di-tert-butyl-4-hydroxybenzoate,     2-methyl-4,6-di-tert-butylphenyl     3,5-di-tert-butyl-4-hydroxybenzoate. -   2.4 Acrylates, for example ethyl lα-cyano-β,β-diphenyl acrylate or     isooctyl αl-cyano-β,β-diphenyl acrylate, methyl     α-carbomethoxycinnamate, methyl     αl-cyano-βl-methyl-p-methoxycinnamate or butyl     α-cyano-β-methyl-p-methoxycinnamate, methyl     αl-carbomethoxy-p-methoxycinnamate and     N-(α-carbomethoxy-β-cyanovinyl)-2-methylindoline. -   2.5 Nickel compounds, for example nickel complexes of     2,2′-thio-bis[4-(1,1,3,3-tetramethylbutyl)phenol], such as the 1:1-     or 1:2-complex, with or without additional ligands, such as     n-butylamine, triethanolamine or N-cyclohexyldiethanolamine, nickel     dibutyldithiocarbamate, nickel salts of monoalkyl esters, such as of     the methyl or ethyl ester, of     4-hydroxy-3,5-di-t-butylbenzylphosphonic acid, nickel complexes of     ketoximes, e.g. of 2-hydroxy-4-methylphenyl undecyl ketoxime, nickel     complexes of 1-phenyl-4-lauroyl-5-hydroxypyrazole, with or without     additional ligands. -   2.6 Sterically hindered amines, for example     bis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate,     bis(2,2,6,6-tetramethylpiperidin-4-yl) succinate,     bis(1,2,2,6,6-pentamethylpiperidin-4-yl)sebacate,     bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate,     bis(1,2,2,6,6-pentamethylpiperidyl)     n-butyl-3,5-di-t-butyl-4-hydroxybenzylmalonate, the condensate of     1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperadine and succinic     acid, the linear or cyclic condensates of     N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and     4-t-octylamino-2,6-dichloro-1,3,5-s-triazine,     tris(2,2,6,6-tetramethyl-4-piperidyl)nitrilotriacetate,     tetrakis(2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetraoate,     1,1′-(1,2-ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone),     4-benzoyl-2,2,6,6-tetramethylpiperidine,     4-stearyloxy-2,2,6,6-tetramethylpiperidine,     bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-t-butylbenzyl)     malonate,     3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione,     bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate,     bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate, the linear     or cyclic condensates of     N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and     4-morpholino-2,6-dichloro-1,3,5-triazine, the condensate of     2-chloro-4,6-di(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine     and 1,2-bis(3-aminopropylamino)ethane, the condensate of     2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazine     and 1,2-bis(3-aminopropylamino)-ethane,     8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione,     3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidine-2,5-dione,     3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione,     a mixture of 4-hexadecyloxy- and     4-stearyloxy-2,2,6,6-tetramethylpiperidine, the condensate of     N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine and     4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, the condensate of     1,2-bis(3-aminopropylamino)ethane and 2,4,6-trichloro-1,3,5-triazine     and also 4-butylamino-2,2,6,6-tetramethylpiperidine (CAS Reg. No.     [136504-96-6]);     N-(2,2,6,6-tetramethyl-4-piperidyl)-n-dodecylsuccinimide,     N-(1,2,2,6,6-pentamethyl-4-piperidyl)-n-dodecylsuccinimide,     2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decane,     the reaction product of     7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decane     and epichlorohydrine,     1,1-bis(1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyl)-2-(4-methoxyphenyl)ether,     N,N′-bis-formyl-N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediamine,     the diester of 4-methoxymethylenemalonic acid with     1,2,2,6,6-pentamethyl-4-hydroxypiperidine,     poly[methylpropyl-3-oxy-4-(2,2,6,6-tetramethyl-4-piperidyl)]siloxane     the reaction product of maleic anhydride-α-olefin copolymer and     2,2,6,6-tetramethyl-4-aminopiperidine or     1,2,2,6,6-pentamethyl-4-aminopiperidine. -   2.7 Oxalamides, for example 4,4′-dioctyloxyoxanilide,     2,2′-diethoxy-oxanilide, 2,2′-dioctyloxy-5,5′-di-butyloxanilide,     2,2′-didodecyloxy-5,5′-di-t-butyloxanilide,     2-ethoxy-2′-ethyloxanilide,     N,N′-bis(3-dimethylaminopropyl)oxalamide,     2-ethoxy-5-t-butyl-2′-ethyloxanilide and its mixture with     2-ethoxy-2′-ethyl-5,4′-di-t-butyloxanilide and mixtures of o- and     p-methoxy- and of o- and p-ethoxy-disubstituted oxanilides. -   2.8 2-(2-Hydroxyphenyl)-1,3,5-triazines, for example     2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine,     2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,     2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,     2,4-bis(2-hydroxy-4-propyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine,     2-(2-hydroxy-4-octyloxyphenyl)-4,6bis(4-methylphenyl)-1,3,5-triazine,     2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,     2-(2-hydroxy-4-tridecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,     2-[2-hydroxy-4-(2-hydroxy-3-butyloxypropyloxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,     2-[2-hydroxy-4-(2-hydroxy-3-octyloxypropyloxy)-phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,     2-[4-(dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5triazine,     2-[2-hydroxy-4-(2-hydroxy-3-dodecyloxy-propoxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,     2-(2-hydroxy-4-hexyloxy)phenyl-4,6-diphenyl-1,3,5-triazine,     2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine,     2,4,6-tris[2-hydroxy-4-(3-butoxy-2-hydroxy-propoxy)phenyl]-1,3,5-triazine,     2-(2-hydroxyphenyl)-4-(4-methoxyphenyl)-6-phenyl-1,3,5-triazine,     2-{2-hydroxy-4-[3-(2-ethylhexyl-1-oxy)-2-hydroxypropyloxy]phenyl}-4,6-bis(2,4-demethylphenyl)-1,3,5-triazine. -   3. Metal deactivators, for example, N,N′-diphenyloxalamide,     N-salicylal-N′-salicyloyl hydrazine, N,N′-bis(salicyloyl)hydrazine,     N,N′-bis(3,5-di-t-butyl-4-hydroxyphenyl-propionyl)hydrazine,     3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxalyl     dihydrazide, oxanilide, isophthaloyl dihydrazide, sebacoyl     bisphenylhydrazide, N,N′-diacetyladipoyl dihydrazide,     N,N′-bis(salicyloyl)oxalyl dihydrazide,     N,N′-bis(salicyloyl)thiopropionyl dihydrazide. -   4. Phosphites, phosphines and phosphonites, for example triphenyl     phosphite, diphenyl alkyl phosphites, phenyl diallyl phosphites,     tris(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl     phosphite, trimethylphosphine, tri-n-butylphosphine,     triphenylphosphine, distearyl pentaerythritol diphosphite,     tris(2,4-di-t-butylphenyl) phosphite, diisodecyl pentaerythritol     diphosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite,     bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite,     bisisodecyloxypentaerythritol diphosphite,     bis(2,4-di-t-butyl-6-methylphenyl)pentaerythritol diphosphite,     bis(2,4,6-tri-t-butylphenyl)pentaerythritol diphosphite, tristearyl     sorbitol triphosphite, tetrakis(2,4-di-t-butylphenyl)     4,4′-biphenylene diphosphonite,     6-isooctyloxy-2,4,8,10-tetra-t-butyl-12H-dibenzo[d,g]-1,3,2-dioxaphosphocin,     6-fluoro-2,4,8,10-tetra-t-butyl-12-methyl-dibenzo[d,g]-1,3,2-dioxaphosphocin,     bis(2,4-di-t-butyl-6-methyl phosphite,     bis(2,4-di-t-butyl-6-methylphenyl) ethyl phosphite,     2,2′,2″-nitrilo[triethyl-tris(3,3′,5,5″tetra-t-butyl-1,1′-biphenyl-2,2′-diyl)phosphite]2-ethylhexyl(3,3′,5,5′-tetra-t-butyl-1,1′-biphenyl-2,2′-diyl)phosphite.

Particular preference is given to using the following phosphites: tris(2,4-Di-t-butylphenyl)phosphite (Irgafos®168, Ciba Specialty Chemicals), tris(nonylphenyl) phosphite and the phosphites selected from the group comprising the structural formulae (a), (b), (c), (d), (e), (f) and (g) given below:

-   5. Hydroxylamines, for example N,N-dibenzylhydroxylamine,     N,N-diethylhydroxylamine, N,N-dioctylhydroxylamine,     N,N-dilaurylhydroxylamine, N,N-ditetradecylhydroxylamine,     N,N-dihexadecylhydroxylamine, N,N-dioctadecylhydroxylamine,     N-hexadecyl-N-octadecylhydroxylamine,     N-heptadecyl-N-octadecylhydroxylamine, N,N-dialkylhydroxylamine from     hydrogenated tallow fatty amines. -   6. Nitrones, for example N-benzyl α-phenyl nitrone, N-ethyl α-methyl     nitrone, N-octyl α-heptyl nitrone, N-lauryl α-undecyl nitrone,     N-tetradecyl α-tridecyl nitrone, N-hexadecyl α-pentadecyl nitrone,     N-octadecyl α-heptadecyl nitrone, N-hexadecyl α-heptadecyl nitrone,     N-octadecyl α-pentadecyl nitrone, N-heptadecyl α-heptadecyl nitrone,     N-octadecyl α-hexadecyl-nitrone, and nitrones derived from     N,N-dialkylhydroxylamines prepared from hydrogenated tallow fatty     amines. -   7. Thiosynergists, for example dilauryl or distearyl     thiodipropionate. -   8. Peroxide scavengers, for example esters of l-thiodipropionic     acid, for example the lauryl, stearyl, myristyl or tridecyl esters,     mercaptobenzimidazole, the zinc salt of 2-mercaptobenzimidazole,     zinc dibutyldithiocarbamate, dioctadecyl disulphide, pentaerythritol     tetrakis-(lβ-dodecylmercapto)propionate. -   9. Polyamide stabilisers, for example copper salts in combination     with iodides and/or phosphorus compounds and salts of divalent     manganese. -   10. Basic co-stabilisers, for example melamine,     polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea     derivatives, hydrazine derivatives, amines, polyamides,     polyurethanes, alkali metal salts and alkaline earth metal salts of     higher fatty acids, for example calcium stearate, zinc stearate,     magnesium behenate, magnesium stearate, sodium ricinoleate,     potassium palmitate, antimony pyrocatecholate or zinc     pyrocatecholate. -   11. Nucleating agents, for example inorganic substances, such as     talc, metal oxides, such as titanium dioxide or magnesium oxide,     phosphates, carbonates or sulphates of, preferably, alkaline earth     metals; organic compounds, such as mono- or polycarboxylic acids and     their salts, such as 4-t-butylbenzoic acid, adipic acid, diphenyl     acetic acid, sodium succinate or sodium benzoate; and polymeric     compounds, for example ionic copolymers (ionomers). -   12. Benzofuranones and indolinones, as described, for example, in     U.S. Pat. No. 4,325,863; U.S. Pat. No. 4,338,244; U.S. Pat. No.     5,175,312, U.S. Pat. No. 5,216,052; U.S. Pat. 5,252,643; DE-A-4 316     611; DE-A-4 316 622; DE-A-4 316 876; EP-A-0 589 839 or EP-A-0 591     102, or     3-[4-(2-acetoxyethoxy)phenyl]-5,7-di-t-butylbenzofuran-2-one,     5,7-di-t-butyl-3-[4-(2-stearoyloxyethoxy)phenyl]benzofuran-2-one,     3,3′-bis[5,7-di-t-butyl-3-(4-[2-hydroxyethoxy]phenyl)benzofuran-2-one],     5,7-di-t-butyl-3-(4-ethoxyphenyl)benzofuran-2-one,     3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-t-butylbenzofuran-2-one,     3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di-t-butylbenzofuran-2-one,     3-(3,4-dimethylphenyl)-5,7-di-t-butylbenzofuran-2-one,     3-(2,3-dimethylphenyl)-5,7-di-t-butylbenzofuran-2-one. -   13. Other additives, for example plasticisers, lubricants,     emulsifiers, pigments, rheological additives, catalysts, levelling     assistants, optical brighteners, flame proofing agents, antistatic     agents or blowing agents. -   A preferred embodiment of the invention relates to an aqueous     dispersion comprising     -   a) 1.0–80.0% (By weight) of a compound of the formula (I);     -   b) 0.1–10.0% Polyvinyl alcohol having a degree of polymerisation         of about 500–2500 and a degree of hydrolysis of about         70.0–99.9%; and, optionally, further additives; and     -   c) Water as the remainder to make 100.0% by weight. -   A particularly preferred embodiment relates to an aqueous dispersion     comprising     -   a) Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate;     -   b) Polyvinyl alcohol having a degree of polymerisation of about         500–2500 and a degree of hydrolysis of about 79.0–94.0%; and,         optionally, further additives; and     -   c) Water as the remainder to make 100.0% by weight. -   A highly preferred embodiment relates to an aqueous dispersion     comprising     -   a) 10.0–60.0% (By weight)         octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate;     -   b) 0.1–10.0% Polyvinyl alcohol having a degree of polymerisation         of about 500–2500 and a degree of hydrolysis of about         79.0–94.0%; and, optionally, further additives; and     -   c) Water as the remainder to make 100.0% by weight. -   Another highly preferred embodiment relates to an aqueous dispersion     comprising     -   a) 40.0–50.0% (By weight)         octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate;     -   b) 1.0–5.0% Polyvinyl alcohol having a degree of polymerisation         of about 500–2500 and a degree of hydrolysis of about         79.0–94.0%; and, optionally, further additives; and     -   c) Water as the remainder to make 100.0% by weight.

The process for preparing the aqueous dispersion defined above is novel and inventive. Therefore, the present invention also relates to a process for preparing the aqueous dispersion defined above which is characterised in that a molten phase of the compound (I) is dispersed in an aqueous phase, wherein polyvinyl alcohol having a degree of polymerisation of about 500–2500 and a degree of hydrolysis of about 70.0–99.9%; and, optionally, further additives are present.

In a preferred embodiment of the process, an emulsion of the o/w-type comprising the components a) and b) within the aqueous phase is obtained. The emulsion is characterised by long storage stability. Another advantage of the process is seen in the fact that crystalline solids of phenolic antioxidants are reduced to desirable particle sizes without wet-grinding the solid. This reduces the costs for preparing dispersions of phenolic antioxidants.

According to a preferred embodiment of the process a solid compound of the formula (I) or mixture with other compounds of the formula (I) is heated, particularly to temperatures between 55° C. and 100° C., to give a melt which is then dispersed in an aqueous dispersion comprising from 2.0 to 20.0% (by weight) polyvinyl alcohol having a degree of polymerisation of about 500–2500 and a degree of hydrolysis of about 70.0–99.9%; and, optionally, further additives. The amount of a compound of the formula (I) to be dispersed may vary within wide limits to give a concentration between about 1.0–80.0% (by weight), preferably 10.0–60.0%, and most preferably 40.0–50.0%, of a compound of the formula (I). The dispersion is made homogeneous by conventional mixing methods, such as the ones known for preparing emulsions. Mixing can be effected by vigorous shaking using a dispersing machine, for example a Vortex mixer, or using dispersing machines of the ®POLYTRON type (Kinematica AG, Littau Switzerland) or dispersing machines produced by IKA (Staufen Germany), a static mixer and conventional stirring machines having a propeller or paddle blade or using a magnetic stirrer or phase mixer.

In order to obtain an especially homogeneous mixture, stirring is carried out at high speed, for example using Y-beam agitators (®Y-Strahl, ®Ultraturrax) or stirring machines produced by Polytron, for example Polytron PT 3000 or DH 30/30 or using a high pressure rotor/stator mixer, for example the BUSS-Mischturbine.

Approximately from 0.1 to 90.0% by weight of the constituents (without the water component), based on the total weight of the dispersion, preferably approximately from 1.0 to 60.0% by weight, can be dispersed in the aqueous phase. In the event that no recrystallisation occurs, the dispersion obtainable can be defined as an emulsion. The emulsion is storage stable under the following conditions, at 0–40° C. for a period of at least 3 months.

By means of analytical measurements from microscopic, laser light scattering or electron micrographs, the size and homogeneity of the particles present in the aqueous dispersion, e.g. droplets or solid particles, is determined.

An average droplet size (×50) of less than 1.5μ for a population of ≧99% (×99)<6.0μ is typical. In the event that solid particles are present, an average particle size (×50) of less than 2.0μ for a population of ≧99% (×99)<15.0μ is observed.

A representative sample, as determined by droplet size analysis by laser light scattering (Sympatec Helos), is characterised by a median droplet size of 1.3μ (×50) and 90%<3.0μ (×90) and a maximum droplet size of <5.0μ (×99).

Subsequent recrystallisation with the conversion to an aqueous dispersion comprising solid particles is carried out, if desired, by inoculating the emulsion with suitable crystal seeds. The crystals present in the aqueous dispersion may then, if desired, be converted to smaller particles sizes by conventional grinding methods, such as wet grinding with a ball mill. Even though the wet grinding step is carried out subsequently, a clear advantage is seen in the fact that crystals of desirable particle size are obtained from a melt rather than other forms of solids, such as powders or precipitates. This prevents the inclusion of air or other undesirable particles.

A further embodiment of the invention relates to the further processing of the aqueous dispersion defined above. The dispersion is particularly suitable for stabilising organic material, especially polymers, specifically styrene (co) polymers, such as polystyrene, ABS (acrylonitrile-butadiene-styrene), IPS (impact polystyrene, graft copolymer of styrene on polybutadiene), MBS (methacrylonitrile-butadiene-styrene) and SBS (styrene-butadiene-styrene). In this context, they act in particular as antioxidants.

Another embodiment the invention relates to polymer compositions comprising

-   -   a′) A compound of the formula (I), wherein R₁, R₂, R₃, x and y         are as defined above and, optionally further additives;     -   b′) Polyvinyl alcohol having a degree of polymerisation of         500–2500 and a degree of hydrolysis of 70.0–99.9%; and     -   c′) The polymer material to be stabilised against oxidative,         thermal or light-induced degradation. Another preferred         embodiment the invention relates to polymer compositions         comprising     -   a′) 1.0–40.0% (By weight) of a compound of the formula (I),         wherein R₁, R₂, R₃, x and y are as defined above and, optionally         further additives;     -   b′) 0.1–5.0% Polyvinyl alcohol having a degree of polymerisation         of 500–2500 and a degree of hydrolysis of 70.0–99.9%; and     -   c′) 10.0–95.0% Polymer material to be stabilised against         oxidative, thermal or light-induced degradation.

The incorporation into the polymer materials can be carried out, for example, by mixing in the composition and, if desired, further additives in accordance with known methods. The incorporation into the polymeric material may take place prior to or during the shaping operation or by applying the composition to the polymer, with or without subsequent evaporation of the solvent. In the case of elastomers, these can also be stabilised as lattices. The invention therefore relates in particular to compositions, wherein the dispersion defined above is incorporated into and/or chemically linked with an elastomer/polymer.

The aqueous dispersion can also be added in the form of a master batch, which contains the individual components defined above in a concentration, for example, of from 2.5 to 25.0% by weight, to the polymer material which is to be stabilised.

The dispersion defined above can expediently be incorporated into polymers by the following methods:

-   -   As emulsion or dispersion (e.g. to lattices or emulsion         polymers);     -   As a dry mix during the mixing in of additional components or         polymer mixtures;     -   By direct addition to the processing apparatus (e.g. extruder,         internal mixer, etc.);     -   As a solution or melt.

Therefore, the present invention also relates to the process for the preparation of the polymer composition, which comprises incorporating within the polymer material to be stabilised against oxidative, thermal or light-induced degradation the aqueous dispersion defined above.

The polymer compositions can be employed in various forms and processed to give various products, for example as or to films, fibres, tapes, moulding compounds or profiles, or as binders for coating materials, adhesives or putties.

Examples of polymer materials to be stabilised are:

-   1. Polymers of monoolefins and diolefins, for example polypropylene,     polyisobutylene, polybut-1-ene, poly4-methylpent-1-ene, polyisoprene     or polybutadiene, as well as polymers of cycloolefins, for example     of cyclopentene, norbornene or dicyclopentadiene; furthermore     polyethylene (which optionally can be crosslinked), for example high     density polyethylene (HDPE), low density polyethylene (LDPE), linear     low density polyethylene (LLDPE), branched low density polyethylene     (BLDPE).

Polyolefins, i.e. polymers of monoolefins exemplified in the preceding paragraph, in particular polyethylene and polypropylene, can be prepared by different, and especially by the following, methods:

-   -   a) Radical polymerisation (normally under high pressure and at         elevated temperature)     -   b) Catalytic polymerisation using a catalyst that normally         contains one or more metals of group IVb, Vb, VIb or VIII of the         Periodic Table. These metals usually have one or more ligands,         such as oxides, halides, alcoholates, esters, ethers, amines,         alkyls, alkenyls and/or aryls that may be either π- or         σ-coordinated. These metal complexes may be in the free form or         fixed on substrates, for example on activated magnesium         chloride, titanium(III) chloride, alumina or silicon oxide.         These catalysts may be soluble or insoluble in the         polymerisation medium. The catalysts can be active as such in         the polymerisation or further activators may be used, for         example metal alkyls, metal hydrides, metal alkyl halides, metal         alkyl oxides or metal alkyloxanes, the metals being elements of         groups Ia, IIa and/or IIIa of the Periodic Table. The activators         may be modified, for example, with further ester, ether, amine         or silyl ether groups. These catalyst systems are usually termed         Phillips, Standard Oil Indiana, Ziegler (Natta), TNZ (DuPont),         metallocene or single site catalysts (SSC).

-   2. Mixtures of the polymers mentioned under 1), for example mixtures     of polypropylene with polyisobutylene, polypropylene with     polyethylene (for example PP/HDPE, PP/LDPE) and mixtures of     different types of polyethylene (for example LDPE/HDPE).

-   3. Copolymers of monoolefins and diolefins with each other or with     other vinyl monomers, for example ethylene-propylene copolymers,     linear low density polyethylene (LLDPE) and mixtures thereof with     low density polyethylene (LDPE), propylene-but-1-ene copolymers,     propylene-isobutylene copolymers, ethylene-but-1-ene copolymers,     ethylene-hexene copolymers, ethylene-methylpentene copolymers,     ethylene-heptene copolymers, ethylene-octene copolymers,     propylene-butadiene copolymers, isobutylene-isoprene copolymers,     ethylene-alkyl acrylate copolymers, ethylene-alkyl methacrylate     copolymers, ethylene-vinyl acetate copolymers and their copolymers     with carbon monoxide or ethylene-acrylic acid copolymers and their     salts (ionomers) as well as terpolymers of ethylene with propylene     and a diene such as hexadiene, dicyclopentadiene or     ethylidene-norbornene; and mixtures of such copolymers with one     another and with polymers mentioned under 1), for example     polypropylene-ethylene-propylene copolymers, LDPE-ethylene-vinyl     acetate copolymers, LDPE-ethylene-acrylic acid copolymers,     LLDPE-ethylene-vinyl acetate copolymers, LLDPE-ethylene-acrylic acid     copolymers and alternating or random polyalkylene-carbon monoxide     copolymers and mixtures thereof with other polymers, for example     polyamides.

-   4. Hydrocarbon resins (for example C₅–C₉) including hydrogenated     modifications thereof (e.g. tackifier resins) and mixtures of     polyalkylenes and starch.

-   5. Polystyrene, poly(p-methylstyrene), poly(alpha-methylstyrene).

-   6. Copolymers of styrene or alpha-methylstyrene with dienes or     acrylic derivatives, for example styrene-butadiene,     styrene-acrylonitrile, styrene-alkyl methacrylate,     styrene-butadiene-alkyl acrylate, styrene-butadiene-alkyl     methacrylate, styrene-maleic anhydride, styrene-acrylonitrile-methyl     acrylate; mixtures of high impact strength of styrene co-polymers     and another polymer, for example a polyacrylate, a diene polymer or     an ethylene-propylene-diene terpolymer; and block copolymers of     styrene such as styrene-butadiene-styrene (SBS),     styrene-isoprene-styrene, styrene-ethylene-butylene-styrene or     styrene-ethylene-propylene-styrene.

-   7. Graft copolymers of styrene or alpha-methylstyrene, for example     styrene on polybutadiene, styrene on polybutadiene-styrene or     polybutadiene-acrylonitrile copolymers, styrene and acrylonitrile     (or methacrylonitrile) on polybutadiene; styrene, acrylonitrile and     methyl methacrylate on polybutadiene; styrene and maleic anhydride     on polybutadiene; styrene, acrylonitrile and maleic anhydride or     maleimide on polybutadiene; styrene and maleimide on polybutadiene,     styrene and alkyl acrylates or alkyl methacrylates on polybutadiene,     styrene and acrylonitrile on ethylene-propylene-diene terpolymers,     styrene and acrylonitrile on polyalkyl acrylates or polyalkyl     methacrylates, styrene and acrylonitrile on acrylate-butadiene     copolymers, as well as mixtures thereof with the copolymers     mentioned under 6), for example the copolymer mixtures known as ABS,     MBS, ASA or AES polymers.

-   8. Halogen-containing polymers such as polychloroprene, chlorinated     rubber, chlorinated or sulphochlorinated polyethylene, copolymers of     ethylene and chlorinated ethylene, epichlorohydrine homo- and     copolymers, especially polymers of halogen-containing vinyl     compounds, for example polyvinyl chloride, polyvinylidene chloride,     polyvinyl fluoride, polyvinylidene fluoride; as well as copolymers     thereof such as vinyl chloride-vinylidene chloride, vinyl     chloride-vinyl acetate or vinylidene chloride-vinyl acetate.

-   9. Polymers derived from α,β-unsaturated acids and derivatives     thereof such as polyacrylates and polymethacrylates, polymethyl     methacrylates, polyacrylamides and polyacrylonitriles,     impact-modified with butyl acrylate.

-   10. Copolymers of the monomers mentioned under 9) with each other or     with other unsaturated monomers, for example acrylonitrile-butadiene     copolymers, acrylonitrile-alkyl acrylate copolymers,     acrylonitrile-alkoxyalkyl acrylate copolymers, acrylonitrile-vinyl     halide copolymers or acrylonitrile-alkyl methacrylate-butadiene     terpolymers.

-   11. Polymers derived from unsaturated alcohols and amines or the     acyl derivatives or acetals thereof, such as polyvinyl alcohol,     polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl     maleate, polyvinyl butyral, polyallyl phthalate or     polyallylmelamine; as well as their copolymers with olefins     mentioned in paragraph 1.

-   12. Homopolymers and copolymers of cyclic ethers such as     polyalkylene glycols, polyethylene oxide, polypropylene oxide or     copolymers thereof with bisglycidyl ethers.

-   13. Polyacetals such as polyoxymethylene and those polyoxymethylenes     that contain comonomers, for example ethylene oxide; polyacetals     modified with thermoplastic polyurethanes, acrylates or MBS.

-   14. Polyphenylene oxides and sulphides, and mixtures thereof with     styrene polymers or polyamides.

-   15. Polyurethanes derived from hydroxyl-terminated polyethers,     polyesters and polybutadienes on the one hand and aliphatic or     aromatic polyisocyanates on the other, as well as precursors     thereof.

-   16. Polyamides and co polyamides derived from diamines and     dicarboxylic acids and/or from aminocarboxylic acids or the     corresponding lactams, such as polyamide 4, 6, 6/6, 6/10, 6/9, 6/12,     4/6, 12/12, 11 and 12, aromatic polyamides starting from m-xylene,     diamine and adipic acid; polyamides prepared from     hexamethylenediamine and isophthalic and/or terephthalic acid and     with or without an elastomer as modifier, for example     poly-2,4,4-trimethylhexamethylene terephthalamide or     poly-m-phenylene isophthalamide. Block copolymers of the     aforementioned polyamides with polyolefins, olefin copolymers,     ionomers or chemically bonded or grafted elastomers; or with     polyethers, e.g. with polyethylene glycol, polypropylene glycol or     polytetramethylene glycol. As well as polyamides or copolyamides     modified with EPDM or ABS; and polyamides condensed during     processing (RIM polyamide systems).

-   17. Polyureas, polyimides, polyamide-imides and polybenzimidazoles.

-   18. Polyesters derived from dicarboxylic acids and dialcohols and/or     from hydroxycarboxylic acids or the corresponding lactones, such as     polyethylene terephthalate, polybutylene terephthalate,     poly-1,4-dimethylolcyclohexane terephthalate, polyhydroxybenzoates,     as well as block polyether esters derived from hydroxyl-terminated     polyethers; and also polyesters modified with polycarbonates or MBS.

-   19. Polycarbonates and polyester carbonates.

-   20. Polysulphones, polyether sulphones and polyether ketones.

-   21. Crosslinked polymers derived from aldehydes on the one hand and     phenols, urea or melamine on the other hand, such as     phenol/formaldehyde resins, urea/formaldehyde resins and     melamine/formaldehyde resins.

-   22. Drying and non-drying alkyd resins.

-   23. Unsaturated polyester resins derived from co polyesters of     saturated and unsaturated dicarboxylic acids with polyhydric     alcohols and vinyl compounds as cross-linking agents, and also     halogen-containing modifications thereof of low flammability.

-   24. Crosslinkable acrylic resins derived from substituted acrylates,     for example from epoxy acrylates, urethane acrylates or polyester     acrylates.

-   25. Alkyd resins, polyester resins and acrylate resins crosslinked     with melamine resins, urea resins, polyisocyanates or epoxy resins.

-   26. Crosslinked epoxy resins derived from polyepoxides, for example     from bisglycidyl ethers, or cycloaliphatic diepoxides.

-   27. Natural polymers such as cellulose, natural rubber, gelatin and     derivatives thereof which have been chemically modified in a     polymer-homologous manner, for example cellulose acetates, cellulose     propionates and cellulose butyrates, or the cellulose ethers such as     methylcellulose; and also rosins and derivatives.

-   28. Blends (polyblends) of the aforementioned polymers, for example     PP/EPDM, polyamide/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS,     PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVC/acrylates, POM/thermoplastic     PUR, PC/thermoplastic PUR, POM/acrylate, POM/MBS, PPO/HIPS, PPO/PA     6.6 and copolymers, PA/HDPE, PA/PP or PA/PPO.

-   29. Aqueous emulsions of natural or synthetic rubbers, for example     natural rubber latex or lattices of carboxylated styrene-butadiene     copolymers.

-   30. Natural and synthetic organic substances which are pure     monomeric compounds or mixtures thereof, for example mineral oils,     animal or vegetable fats, oils and waxes, or oils, waxes and fats     based on synthetic esters (e.g. phthalates, adipates, phosphates or     trimellitates), and also blends of synthetic esters with mineral     oils in any desired proportions by weight, as are employed, for     example, as spin finishes, and also the aqueous emulsions thereof.

The invention also relates to compositions comprising the components a′), b′) and c′) and additives customarily present in polymer compositions.

Such additives can be added in small amounts, e.g. UV absorbers or light stabilisers, for example from the series of hydroxyphenylbenzotriazoles, hydroxyphenylbenzophenones, oxalamides and hydroxyphenyl-s-triazines. Especially suitable are light stabilisers from the group of so-called sterically hindered amines (HALS), e.g. the 2-(2-hydroxyphenyl)-1,3,5-triazine or 2-hydroxyphenyl-2H-benzotriazol types. Examples of light stabilisers of the 2-(2-hydroxyphenyl)-1,3,5-triazine type are known from the patent literature, e.g. U.S. Pat. No. 4,619,956, EP-A-434 608, U.S. Pat. No. 5,198,498, U.S. Pat. No. 5,322,868, U.S. Pat. No. 5,369,140, U.S. Pat. No. 5,298,067, WO-94/18278, EP-A-704 437, GB-A-2 297 091 or WO-96/28431.

The polymer compositions defined above may comprise additional additives, too, for example thickeners, fillers, e.g. calcium carbonate, silicates, glass or glass fibre material, talcum, kaolin, mica, barium sulphate, metal oxides and hydroxides, carbon black, graphite, powdered wood and powdered or fibrous material of other natural products, synthetic fibres, plasticisers, lubricants, emulsifiers, pigments, flow auxiliaries, catalysts, optical brighteners, flame-retardants, antistatics and blowing agents.

The compositions according to the present invention can be used for a very wide variety of technical applications, for example as adhesives, detergent adjuvants, detergents, dispersants, emulsifiers, surfactants, antifoams, tackifiers, corrosion inhibitors, viscosity improvers, lubricants, flow improvers, thickeners, cross linking agents, as additives for water treatment, electronic materials, paints and lacquers, coatings, inks, photo developers, super absorbents, cosmetics, preservatives, or as biocides or modifiers and adjuvants for asphalt, textiles, ceramics and wood.

The following Examples illustrate the invention (s: second(s); min: minutes; h: hour(s); temperatures in degrees Celsius (° C.); rpm: rotations per minute; l: liter(s); percentages in weight percent based on the total weight of the composition):

EXAMPLE 1 Preparation of an Aqueous, Non-ionic Emulsion of 50 Weight % octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate

350 g Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate (=IRGANOX 1076) powder are melted at 55° C. in a 1 l glass reaction vessel. 350 g of an aqueous non-ionic surfactant solution is prepared in a 1,5 l sulphuration flask by adding 28 g MOWIOL 8–88 (degree of hydrolysis: 87–89%) to 322 g deionised cold water under stirring. The suspension is then heated up to 80–85° C. for 1 hour to ensure a complete dissolution. The clear colourless solution is then cooled to 25° C. The molten mass of low viscosity is dosed to the cooled surfactant solution at 53–55° C. during 30 min and dispersed vigorously for 35–40 min using a Y-beam stirrer (10 000 to 15 000 rpm, 45 mm diameter), keeping the dispersion at 25–30° C. with a water bath.

A storage stable, finely dispersed o/w emulsion of 50% IRGANOX 1076 is obtained which has the following properties:

-   -   pH: 6.2–6.5     -   Droplet size distribution (laser light diffraction analysis with         Sympatec analyser Helos): median value (×50)=1.2–1.4μ and         percentage of droplet >5.0μ lower than 1% (×99 <5μ)     -   Dynamic viscosity (at 25° C., depends on shear velocity         (viscoelastic)): 875 mPa·s at 139/s and 1270 mPa·s at 58/s         (Haake viscosimeter type VT50, rotative element: MV DIN)     -   Storage stability at 40° C.: no phase separation no         crystallisation within 3 months

No crystallisation is observed after inoculation of seed crystals at a storage temperature up to 40° C.

EXAMPLE 2

108 g IRGANOX 1076 are melted at 60° C. in a 1 l glass reaction vessel. 432 g Ethylene-bis (oxyethylene)-bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)-propionate] (=IRGANOX 245) are added in portions to the molten mass and dissolved therein at 80–90° C. 660 g of an aqueous non-ionic surfactant dispersion is prepared in a 1.5 l sulphuration flask by adding and dissolving 60 g MOWIOL 8–88 to 600 g deionised water like in Example 1. The solution is kept at 85° C. in a water bath. The molten mixture of moderate viscosity (160 mPa·s) is added at 90° C. for 15–20 min to the surfactant solution and then emulgated at 85–87° C. under medium agitation (propeller stirrer, 500–700 rpm) to obtain a droplet size from up to 30μ. At the end of the addition the emulsion is further emulgated for further 30 min by stirring with a Y-beam stirrer at a speed varying from 5 000 up to 15 000 rpm. The emulsion is then cooled down for 15 min under normal stirring (propeller stirrer, 250 rpm) to room temperature.

A storage stable, finely dispersed emulsion is obtained, which has the following properties:

-   -   Microscopic and laser diffraction analysis reveal a median         droplet size of 1.1μ and a maximum droplet size (×99) of 3.1μ     -   The flow properties of the emulsion are Newtonian. Dynamic         viscosity: 585–600 mPa·s at 25° C. (Viscosimeter type HAAKE         VT50, rotative element MV DIN)     -   The emulsion is storage stable at least 1 week at room         temperature. Suitable by-products (<0.2% by weight) can be added         to increase the shelf time if desired     -   Partial recrystallisation of IRGANOX 245 can be observed during         storage at T>25° C. especially at the interface liquid/air. 

1. A process for preparing an aqueous emulsion comprising a) a compound of the formula:

wherein one of R₁ and R₂ independently of one another represents hydrogen or C₁–C₄alkyl and the other one represents C₃–C₄alkyl; x represents zero (direct bond) or a numeral from one to three; and R₃ represents C₈–C₂₂alkyl or a group of the partial formulae

wherein one of R₁′ and R₂′ independently of one another represents hydrogen or C₁–C₄alkyl and the other one represents C₃–C₄alkyl; x represents zero (direct bond) or a numeral from one to three; and y represents a numeral from two to six; b) polyvinyl alcohol having a degree of polymerisation of about 500–2500 and a degree of hydrolysis of about 70.0–99.9%; and, optionally, further additives; and c) water, which process comprises dispersing a molten phase of component (a) in an aqueous phase, where polyvinyl alcohol of component (b) and optionally further additives are present.
 2. A process according to claim 1 for preparing an aqueous emulsion comprising a) 1.0–80.0% (by weight) of a compound of the formula (I); b) 0.1–10.0% polyvinyl alcohol having a degree of polymerisation of about 500–2500 and a degree of hydrolysis of about 70.0–99.9%; and, optionally, further additives; and c) water as the remainder to make 100.0% by weight.
 3. A process according to claim 1 for preparing an aqueous emulsion comprising a) octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate; b) polyvinyl alcohol having a degree of polymerisation of about 500–2500 and a degree of hydrolysis of about 79.0–94.0%; and, optionally, further additives; and c) water as the remainder to make 100.0% by weight.
 4. A process according to claim 3 for preparing an aqueous emulsion comprising a) 10.0–60.0% (by weight) octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate; b) 0.1–10.0% polyvinyl alcohol having a degree of polymerisation of about 500–2500 and a degree of hydrolysis of about 79.0–94.0%; and, optionally, further additives; and c) water as the remainder to make 100.0% by weight.
 5. A process according to claim 3 for preparing an aqueous emulsion comprising a) 40.0–50.0% (by weight) octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; b) 1.0–5.0% polyvinyl alcohol having a degree of polymerisation of about 500–2500 and a degree of hydrolysis of about 79.0–94.0%; and, optionally, further additives; and c) water as the remainder to make 100.0% by weight. 